Shrub Production and Biomass Trends Following Five Logging Treatments Within the Cedar-Hemlock Zone of Northern Idaho
Abstract:Trends through time are presented for shrub biomass, twig production, height growth, percent cover, and composition following thinning and four forest regeneration treatments within three habitat types of the cedar-hemlock zone of northern Idaho. Regression analyses yielded prediction equations for the above variables. Most shrub species occurred within a specific habitat type and harvest treatment. The probability of occurrence of all but one shrub showed no relationship with time following cutting, since most existed in the stands prior to logging or prior to sampling, which occurred at least 5 years after cutting. Shrubs less than 1 m tall most often predominated in selection, seedtree, and shelterwood cuttings, while more midsized and tall shrubs occurred within clearcuts. Growth in height of most shrubs was related to time since cutting and amount of overstory remaining after cutting. Growth rates of some were related to elevation and specific aspects. Differences in percent cover of individual species were related to habitat type as well as time since cutting. Maximum shrub biomass production occurred 10 to 14 years after cutting. Clearcuts produced the most and partial cuttings the least shrub biomass and twigs per unit area, respectively. The western red cedar (Thuja plicata) and grand fir (Abies grandis) habitat types were more productive of twigs than western hemlock (Tsuga heterophylla). Thinnings within the three habitat types produced few changes in shrub composition and growth except those cases where tall shrubs responded to actual damage by resprouting from the root crown. Composition was variable but trends in shrub succession following the five silvicultural treatments were most influenced by presence or absence of midsized species such as shinyleaf ceanothus (Ceanothus velutinus) or redstem (C. sanguineus), which rapidly responded to slash burning, particularly to broadcast burning in clearcuts. Forest Sci. 25:415-426.
Document Type: Journal Article
Affiliations: Professor in the College of Forestry, Wildlife and Range Sciences, University of Idaho, Moscow
Publication date: September 1, 1979
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